<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK IT ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006-2012 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------

define('CLIENT_MULTI_RESULTS', 131072);
/**
 * ThinkPHP 简洁模式数据库中间层实现类
 * 只支持mysql
 */
class Db {

	static private $_instance = null;
	// 是否自动释放查询结果
	protected $autoFree         = false;
	// 是否显示调试信息 如果启用会在日志文件记录sql语句
	public $debug             = false;
	// 是否使用永久连接
	protected $pconnect         = false;
	// 当前SQL指令
	protected $queryStr          = '';
	// 最后插入ID
	protected $lastInsID         = null;
	// 返回或者影响记录数
	protected $numRows        = 0;
	// 返回字段数
	protected $numCols          = 0;
	// 事务指令数
	protected $transTimes      = 0;
	// 错误信息
	protected $error              = '';
	// 当前连接ID
	protected $linkID            =   null;
	// 当前查询ID
	protected $queryID          = null;
	// 是否已经连接数据库
	protected $connected       = false;
	// 数据库连接参数配置
	protected $config             = '';
	// 数据库表达式
	protected $comparison      = array('eq'=>'=','neq'=>'!=','gt'=>'>','egt'=>'>=','lt'=>'<','elt'=>'<=','notlike'=>'NOT LIKE','like'=>'LIKE');
	// 查询表达式
	protected $selectSql  =     'SELECT%DISTINCT% %FIELDS% FROM %TABLE%%JOIN%%WHERE%%GROUP%%HAVING%%ORDER%%LIMIT%';
	/**
	 * 架构函数
	 * @access public
	 * @param array $config 数据库配置数组
	 */
	public function __construct($config=''){
		if ( !extension_loaded('mysql') ) {
			throw_exception(L('_NOT_SUPPERT_').':mysql');
		}
		$this->config   =   $this->parseConfig($config);
	}

	/**
	 * 连接数据库方法
	 * @access public
	 * @throws ThinkExecption
	 */
	public function connect() {
		if(!$this->connected) {
			$config =   $this->config;
			// 处理不带端口号的socket连接情况
			$host = $config['hostname'].($config['hostport']?":{$config['hostport']}":'');
			if($this->pconnect) {
				$this->linkID = mysql_pconnect( $host, $config['username'], $config['password'],CLIENT_MULTI_RESULTS);
			}else{
				$this->linkID = mysql_connect( $host, $config['username'], $config['password'],true,CLIENT_MULTI_RESULTS);
			}
			if ( !$this->linkID || (!empty($config['database']) && !mysql_select_db($config['database'], $this->linkID)) ) {
				throw_exception(mysql_error());
			}
			$dbVersion = mysql_get_server_info($this->linkID);
			if ($dbVersion >= "4.1") {
				//使用UTF8存取数据库 需要mysql 4.1.0以上支持
				mysql_query("SET NAMES '".C('DB_CHARSET')."'", $this->linkID);
			}
			//设置 sql_model
			if($dbVersion >'5.0.1'){
				mysql_query("SET sql_mode=''",$this->linkID);
			}
			// 标记连接成功
			$this->connected    =   true;
			// 注销数据库连接配置信息
			unset($this->config);
		}
	}

	/**
	 * 释放查询结果
	 * @access public
	 */
	public function free() {
		mysql_free_result($this->queryID);
		$this->queryID = 0;
	}

	/**
	 * 执行查询 主要针对 SELECT, SHOW 等指令
	 * 返回数据集
	 * @access public
	 * @param string $str  sql指令
	 * @return mixed
	 * @throws ThinkExecption
	 */
	public function query($str='') {
		$this->connect();
		if ( !$this->linkID ) return false;
		if ( $str != '' ) $this->queryStr = $str;
		//释放前次的查询结果
		if ( $this->queryID ) {    $this->free();    }
		N('db_query',1);
		// 记录开始执行时间
		G('queryStartTime');
		$this->queryID = mysql_query($this->queryStr, $this->linkID);
		$this->debug();
		if ( !$this->queryID ) {
			if ( $this->debug )
			throw_exception($this->error());
			else
			return false;
		} else {
			$this->numRows = mysql_num_rows($this->queryID);
			return $this->getAll();
		}
	}

	/**
	 * 执行语句 针对 INSERT, UPDATE 以及DELETE
	 * @access public
	 * @param string $str  sql指令
	 * @return integer
	 * @throws ThinkExecption
	 */
	public function execute($str='') {
		$this->connect();
		if ( !$this->linkID ) return false;
		if ( $str != '' ) $this->queryStr = $str;
		//释放前次的查询结果
		if ( $this->queryID ) {    $this->free();    }
		N('db_write',1);
		// 记录开始执行时间
		G('queryStartTime');
		$result =   mysql_query($this->queryStr, $this->linkID) ;
		$this->debug();
		if ( false === $result) {
			if ( $this->debug )
			throw_exception($this->error());
			else
			return false;
		} else {
			$this->numRows = mysql_affected_rows($this->linkID);
			$this->lastInsID = mysql_insert_id($this->linkID);
			return $this->numRows;
		}
	}

	/**
	 * 启动事务
	 * @access public
	 * @return void
	 * @throws ThinkExecption
	 */
	public function startTrans() {
		$this->connect(true);
		if ( !$this->linkID ) return false;
		//数据rollback 支持
		if ($this->transTimes == 0) {
			mysql_query('START TRANSACTION', $this->linkID);
		}
		$this->transTimes++;
		return ;
	}

	/**
	 * 用于非自动提交状态下面的查询提交
	 * @access public
	 * @return boolen
	 * @throws ThinkExecption
	 */
	public function commit() {
		if ($this->transTimes > 0) {
			$result = mysql_query('COMMIT', $this->linkID);
			$this->transTimes = 0;
			if(!$result){
				throw_exception($this->error());
				return false;
			}
		}
		return true;
	}

	/**
	 * 事务回滚
	 * @access public
	 * @return boolen
	 * @throws ThinkExecption
	 */
	public function rollback() {
		if ($this->transTimes > 0) {
			$result = mysql_query('ROLLBACK', $this->linkID);
			$this->transTimes = 0;
			if(!$result){
				throw_exception($this->error());
				return false;
			}
		}
		return true;
	}

	/**
	 * 获得所有的查询数据
	 * @access public
	 * @return array
	 * @throws ThinkExecption
	 */
	public function getAll() {
		if ( !$this->queryID ) {
			throw_exception($this->error());
			return false;
		}
		//返回数据集
		$result = array();
		if($this->numRows >0) {
			while($row = mysql_fetch_assoc($this->queryID)){
				$result[]   =   $row;
			}
			mysql_data_seek($this->queryID,0);
		}
		return $result;
	}

	/**
	 * 关闭数据库
	 * @access public
	 * @throws ThinkExecption
	 */
	public function close() {
		if (!empty($this->queryID))
		mysql_free_result($this->queryID);
		if ($this->linkID && !mysql_close($this->linkID)){
			throw_exception($this->error());
		}
		$this->linkID = 0;
	}

	/**
	 * 数据库错误信息
	 * 并显示当前的SQL语句
	 * @access public
	 * @return string
	 */
	public function error() {
		$this->error = mysql_error($this->linkID);
		if($this->queryStr!=''){
			$this->error .= "\n [ SQL语句 ] : ".$this->queryStr;
		}
		return $this->error;
	}

	/**
	 * SQL指令安全过滤
	 * @access public
	 * @param string $str  SQL字符串
	 * @return string
	 */
	public function escapeString($str) {
		return mysql_escape_string($str);
	}

	/**
	 * 析构方法
	 * @access public
	 */
	public function __destruct() {
		// 关闭连接
		$this->close();
	}

	/**
	 * 取得数据库类实例
	 * @static
	 * @access public
	 * @return mixed 返回数据库驱动类
	 */
	public static function getInstance($db_config='') {
		if ( self::$_instance==null ){
			self::$_instance = new Db($db_config);
		}
		return self::$_instance;
	}

	/**
	 * 分析数据库配置信息，支持数组和DSN
	 * @access private
	 * @param mixed $db_config 数据库配置信息
	 * @return string
	 */
	private function parseConfig($db_config='') {
		if ( !empty($db_config) && is_string($db_config)) {
			// 如果DSN字符串则进行解析
			$db_config = $this->parseDSN($db_config);
		}else if(empty($db_config)){
			// 如果配置为空，读取配置文件设置
			$db_config = array (
                'dbms'        =>   C('DB_TYPE'),
                'username'  =>   C('DB_USER'),
                'password'   =>   C('DB_PWD'),
                'hostname'  =>   C('DB_HOST'),
                'hostport'    =>   C('DB_PORT'),
                'database'   =>   C('DB_NAME'),
                'dsn'          =>   C('DB_DSN'),
                'params'     =>   C('DB_PARAMS'),
			);
		}
		return $db_config;
	}

	/**
	 * DSN解析
	 * 格式： mysql://username:passwd@localhost:3306/DbName
	 * @static
	 * @access public
	 * @param string $dsnStr
	 * @return array
	 */
	public function parseDSN($dsnStr) {
		if( empty($dsnStr) ){return false;}
		$info = parse_url($dsnStr);
		if($info['scheme']){
			$dsn = array(
            'dbms'        => $info['scheme'],
            'username'  => isset($info['user']) ? $info['user'] : '',
            'password'   => isset($info['pass']) ? $info['pass'] : '',
            'hostname'  => isset($info['host']) ? $info['host'] : '',
            'hostport'    => isset($info['port']) ? $info['port'] : '',
            'database'   => isset($info['path']) ? substr($info['path'],1) : ''
            );
		}else {
			preg_match('/^(.*?)\:\/\/(.*?)\:(.*?)\@(.*?)\:([0-9]{1, 6})\/(.*?)$/',trim($dsnStr),$matches);
			$dsn = array (
            'dbms'        => $matches[1],
            'username'  => $matches[2],
            'password'   => $matches[3],
            'hostname'  => $matches[4],
            'hostport'    => $matches[5],
            'database'   => $matches[6]
			);
		}
		return $dsn;
	}

	/**
	 * 数据库调试 记录当前SQL
	 * @access protected
	 */
	protected function debug() {
		// 记录操作结束时间
		if ( $this->debug ) {
			G('queryEndTime');
			Log::record($this->queryStr." [ RunTime:".G('queryStartTime','queryEndTime',6)."s ]",Log::SQL);
		}
	}

	/**
	 * 获取最近一次查询的sql语句
	 * @access public
	 * @return string
	 */
	public function getLastSql() {
		return $this->queryStr;
	}

	/**
	 * 获取最近插入的ID
	 * @access public
	 * @return string
	 */
	public function getLastInsID(){
		return $this->lastInsID;
	}
}